The invention relates to a holding arrangement for a steering column of a motor vehicle. The preferred embodiments relate to holding arrangements with a steering column supporting a steering wheel and an air bag therein.
In the case of a collision that severely decelerates the vehicle, the driver is thrown forward at a high relative speed with respect to the vehicle and impacts against the steering wheel. Now the kinetic energy that is generated during the forward motion of mainly the upper part of the driver's body is to be absorbed by a plastic deformation while energy is absorbed in the steering system and as a result an injury to the driver is to be largely eliminated. From German Patent (DE-PS) 26 23 521, a cylindrical deformation element having recesses arranged in the steering column has become known that permits this type of energy absorption. In the case of a steering system with an air bag arranged in the steering wheel, it is, because of the space in the steering wheel that is required for this purpose, no longer possible to install this deformation element.
In order to achieve an effect that essentially corresponds to that using a cylindrical deformation element, it is known from German Patent (DE-PS) 21 43 935 to connect the steering protection tube surrounding the steering column via a supporting bracket with the vehicle body, in which case this supporting bracket is developed as an energy-absorbing deformation element and has a weakened area developed as the deforming element, said weakened area being located in a horizontal approximately parallel plane that is arranged with respect to the impinging force. By means of this type of development of the supporting bracket, essentially only a deformation in the direction of the impact force is possible, whereas no yielding adjustment of the steering column in vertical direction is achieved. In addition, this type of known supporting bracket with the weakened area in the horizontal plane has a desired softness that does not make it possible to ensure a suppression of a trembling of the steering wheel in the driving operation.
An objective of the invention is to provide a holding arrangement for a steering system that has a targeted softness for a deformation in the case of an impact and at the same time a stiffness that is as extensive as possible for a bearing of the steering system that is free from vibrations.
According to the invention, this objective is achieved by providing a carrier bracket with deformation sections supporting one side of the steering column protection tube and a knee support arrangement engaging the other side of the protection tube.
The main advantages achieved by means of the invention are that a relatively stiff holding arrangement for the steering system at the same time serves as the only deformation element in the steering system and ensures sufficient energy absorption in the case of an impact. Because of the special position of the deformation sections at a narrow side of the openings in the lateral parts, only an insufficient deformation of the supporting bracket and thus no sufficiently effective energy absorption can be achieved by means of the longitudinally directed impact force and by means of a vertical component with respect to it alone, particularly since a bearing sheet connected with the steering protection tube acts as the stiffening element.
In order to achieve an optimized energy absorption, the longitudinal force that is introduced via the steering wheel is supplemented by an additional vertical force that is introduced into the steering protection tube via a knee catching device and a support. This force is generated when the driver's knees impact at the knee catching device that is cushioned on the outside but via which nevertheless a force component via the support is introduced into the steering protection tube. This force component preferably affects the protection tube at a position in front of the supporting bracket with respect to the steering wheel so that an upward-swivelling motion of the steering column and a deformation of the supporting bracket that is adapted to the conditions can be achieved.
Advantageously, the support may either be rigidly connected with the steering protection tube or the support is arranged at a distance to the steering protection tube, according to certain preferred embodiments. In addition, it is also contemplated to fasten the support at the steering protection tube, in which case, it would then be located at a distance opposite a carrying means of the knee catching device according to certain preferred embodiments.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.